The overall objective of this research is to gain in understanding the function of complex carbohydrate chains on the surface of somatic cells. Few glycoproteins occurring as natural cell surface molecules on somatic cells have had their saccharide chains defined in detail. We propose to establish the chemical structure of the glycopeptides derived from the "Large, External, Transformation-Sensitive" (LETS) glycoprotein with is specific for fibroblasts, glial and trophoblast cell surfaces, and also occurs in the plasma as the "Cold Insoluble Globulin" (CIg). We also plan to compare the structures of the cell-surface derived LETS and the plasma-derived CIg.